1. Field of the Invention
This invention relates to compounds which are bradykinin receptor antagonists, pharmaceutical compositions and methods for using these compounds to antagonize the effects of bradykinin in mammals, including humans. More particularly, the invention relates to the substitution of the L-Pro at position 7 with D-hydroxyproline ether or thioether compounds and its intermediate product which convert bradykinin agonists into antagonists and also includes additional modifications at other positions within the 7-position modified bradykinin antagonist which confer increased antagonist potency, resistance to enzymatic degradation, and/or tissue specificity on the D-amino acid-containing bradykinin sequence.
2. Description of the Prior Art
Bradykinin (BK) is a nonapeptide generated as a result of the activity of kallikreins, a group of proteolytic enzymes present in most tissues and body fluids, on kininogens. Once released, kinins produce many physiological responses, including pain and hyperanalgesia by stimulating C- and A-fibers in the periphery. There is also considerable evidence that kinins contribute to the inflammatory response.
Bradykinin, and its physiologically important related peptides kallidin (Lys-bradykinin) and Met-Lys-bradykinin, exhibit physiological actions which qualify them as mediators of inflammatory reactions, hypotensive states, and pain. Bradykinin is overproduced in pathological conditions such as septic shock, anaphylaxis, rhinitis, asthma, inflammatory bowel disease, and certain other conditions including acute pancreatitis, post-gastrectomy dumping syndrome, carcinoid syndrome, migraine, and angioneurotic edema. The production of bradykinin from the plasma results in pain at the site of the pathological condition, and the overproduction intensifies the pain directly or via bradykinin-induced activation of the arachidonic acid pathway which produces prostaglandins and leukotrienes, the more distal and actual mediators of inflammation.
In addition to its analgesic and proinflammatory effects, bradykinin is a vasodilator. Because of its ability to lower blood pressure, bradykinin has been implicated in the pathogenesis of several shock syndromes, particularly septic or endotoxic shock. Bradykinin is also a potent bronchoconstrictor in animals and asthmatic subjects and it has been implicated as a contributor to the pathogenesis of airway inflammatory conditions such as allergic asthma and rhinitis.
Thus, a bradykinin inhibitor or bradykinin receptor antagonist is expected to possess a number of desirable biological effects in the treatment, for example, of inflammation, septic shock, asthma, burn pain, rhinitis, and allergy.
The search for understanding the mechanism of action of bradykinin, which is essential for the development of useful tools for diagnostic use, and for the development of therapeutic agents aimed at alleviating the intense pain caused by the production and overproduction of bradykinin, has been hindered by the lack of specific sequence-related competitive antagonists of bradykinin.
Several non-peptide, non-specific and non-selective antagonists of one or more of the biological activities of bradykinin have been described among compounds as diverse as analgesics and anti-inflammatory substances, which act via the prostaglandin system and not directly on bradykinin receptors. These are antihistamines; bradykinin-antibodies; benzodiazepine derivatives; high molecular weight ethylene oxide polymers; gallic acid esters; and serotonin inhibitors. None of these compounds or classes of compounds specifically inhibit the effects of bradykinin.
Heptyl esters of various amino acid-containing substances, such as single basic amino acids, the dipeptide Phe-Gly, and analogs of C- terminal peptide fragments of bradykinin (i.e., Pro-Phe-Arg) have been reported as anti-bradykinin substances. When tested in bradykinin assay systems, they prove to be weak partial agonists/antagonists, depending on the dose, with little specificity for inhibiting bradykinin action.
Preparations of damaged vascular tissue have been reported to respond to bradykinin analogs which lack the C-terminal arginine residue, but not to bradykinin itself, and analogs of these des-Arg(9)-bradykinins have been developed as antagonists for the non-physiological activity of bradykinin. These antagonists have no significant bradykinin-like agonist effects, nor any antagonist effect on any of the physiologically significant kinin-responding systems. Furthermore, several bradykinin analogs containing the O-methyl ether of Tyr residues at positions 5 and/or 8 have been reported to produce mixed agonist/antagonist activity on isolated uteri of galactosemic rats, but not on normal rats.
Other changes in the bradykinin molecule have been additions of amino acids at the N-terminal end which affect the rate of enzymatic degradation of bradykinin in vivo.
It has been reported that the half life of bradykinin in the systemic circulation is less than 30 seconds. Bradykinin appears to be completely destroyed (98-99% destruction) on a single passage through the pulmonary circulation as determined in an anesthetized rat by measuring the depressor effects of an agonist following intra-aortic (IA) (bypassing the pulmonary circulation) and intravenous (IV) administration. Resistance of bradykinin agonists to pulmonary kininase destruction in vivo also appears promoted by addition of single (i.e., D-Arg-, D-Lys-, Lys-) and double (D-Lys-Lys-) basic amino acid residues to the N-terminal of the bradykinin sequence. The addition of the dipeptide Lys-Lys to the N-terminal of bradykinin agonists has been reported to confer complete resistance to in vivo destruction on initial passage through the pulmonary circulation.
Several research groups have prepared bradykinin receptor antagonists. Stewart and Vavrek in U.S. Pat. No. 4,801,613, (which reference is incorporated in its entirety herein) disclose a series of bradykinin antagonists wherein the L-Pro at the 7-position of the peptide hormone bradykinin or other substituted analogs of bradykinin is substituted with an aromatic amino acid of the D-configuration which converts bradykinin agonists into bradykinin antagonists. The analogs produced are useful in treating conditions and diseases of a mammal and human in which an excess of bradykinin or related kinins are produced or injected as by insect bites into the body. The specific L-Pro substitutions are selected from the group consisting of D-Nal, D-PNF, D-Phe, D-Tyr, D-Pal, D-OMT, D-Thi, D-Ala, D-Trp, D-His, D-Homo-Phe, D-Phe, pCl-D-Phe (CDF), D-Phg, D-Val, D-Ile, D-Leu, and MDY.
In U.S. Pat. No. 4,693,993, also to Stewart and Vavrek, additional L-Pro substitution materials are disclosed.
Application Ser. No. 687,950 filed Apr. 19, 1991, now abandoned, discloses and claims additional L-Pro substitution materials with hydroxyproline ether and thioether compounds.
U.S. Pat. No. 4,242,329 to Claeson et al. disclose the formation of Bradykinin-inhibiting tripeptide derivatives. A process for producing said tripeptide derivatives by synthesis and purification methods which are known in the peptide chemistry is also disclosed as well as pharmaceutical preparations comprising the tripeptide derivative.
Published European Patent Applications No. 0 413 277 A1 and 0 370 453 AZ disclose bradykinin antagonists.